Noninvasive Characterization of Myocardial Diseases With Hypertrophic Phenotypes Using Integrated ECG/Echocardiographic Indices

Background: Indices reflecting the discordance between QRS complex voltages on ECG and left ventricular (LV) wall thickness or LV mass index on echocardiogram (echo) have enabled identification of cardiac amyloidosis (CA) among patients with hypertrophic hearts. However, this evidence comes from studies that have excluded patients with established hypertrophic cardiomyopathy (HCM) and Anderson-Fabry disease (AFD). The aim of this study was to assess the performance of ECG/echo indices in characterizing adult patients with cardiomyopathies and hypertrophic phenotype. Methods: This was an Italian retrospective, cross-sectional, multicenter study. Data from ECGs and echo of consecutive adult patients with confirmed CA, HCM, and AFD, and an LV wall thickness >12 mm were analyzed to calculate different ECG/echo indices. Results: Of the 1181 patients included (median age, 65 years; 69% men), 35.5% (n=416) had CA, 46.5% (n=594) had HCM, and 14.5% (n=171) had AFD. All ECG/echo indices were able to distinguish CA from other HCM and AFD (P<0.001). The total QRS score/LV mass index was the best performing ECG/echo index for differentiating CA from other hypertrophic phenotypes (accuracy: 83%). The total QRS/maximum LV wall thickness was the best performing index in discriminating between the 3 cardiomyopathies (cutoff values of 6.21 versus 9.81 versus 11.47 in CA, HCM, AFD, respectively; P<0.001 for all comparisons). Conclusions: ECG/echo indices, particularly total QRS/maximum LV wall thickness, may serve as easily accessible first-line tools to differentiate CA from HCM and AFD. These findings may enable prompt recognition of patients with different cardiomyopathies in everyday clinical practice, both in community-based centers and tertiary care facilities, and to orient subsequent diagnostic workup.